Screening mammography has proven to be an effective procedure for the detection of early breast cancer. However, a significant fraction of cancer escapes detection due to dense glandular tissue which obscures the underlying pathology. Diffraction Enhanced x-ray Imaging (DEI) has the potential to dramatically change mammography and radiography in general. Specifically developed as part of an x-ray mammography program utilizing monochromatic x-rays from a synchrotron source, this technique has produced images of test objects and issue whose contrast and information content far exceeds conventional techniques. Preliminary work with human breast cancer specimens suggests that DEI images include information regarding specific physical characteristics of the lesion including border detail and associated features that are not detected by conventional imaging. The long term goal of this program is to develop a clinical based DEI system for mammography. The first phase of this program is to identify the optimal DEI parameters for improved visualization of lesions of the breast and to use these parameters to develop a conceptual design of a clinical DEI system. The synchrotron provides the ideal environment to perform these pilot studies since it provides a very intense, collimated, and tunable source of x-radiation. Specifically, a study of human breast tissue samples with cancer will be performed in which the DEI parameters will be systematically assessed regarding the visibility of structures suggestive of breast cancer-namely, spiculation architectural distortion, and calcification. This study will include the assessment of a wide variety of DEI parameters including imaging energy, refraction/scatter-rejection sensitivity, location on the "rocking curve," and x-ray optical geometry. The intent of this study is to optimize DEI for the clinical task. This will allow us to specify the x-ray source, x-ray optics, and detection method requirements for a clinical based system. As a result of this work the applicants propose to develop a conceptual design for a clinical system for mammography using DEI.